When using the web, long response times are bonesof contention for users, i.e. they damp the Quality of Experience (QoE). Though, if one knows the cause of the long response time one may examine what could be done to eliminate the obstacle. In this paper, we determine the weak point of the Extensible Authentication Protocol Method for GSM Subscriber Identity Modules (EAP-SIM) with the OpenID service with regards to excessive authentication times, which determine the response times. In order to provoke controlled increases of the latter, we emulate bad network performance by introducing bi-directional delay between the supplicant (client) and the authentication server. The same procedure is also applied to several other EAP methods. Based on a recent, exponential relationship between QoE and response time, we then identify, quantify and compare the decisive factors for QoE reduction as functions of the components of the authentication times. The results we obtain clearly show that one task of the EAP-SIM authentication contributes significantly more to the total response times than the other tasks, which points out the direction for future optimisation of user perception of authentication times.